Cutting electrodes are used in medicine to remove tissue, typically in urology and, in that field, especially for purposes of prostate resection. The cutting electrode is connected to a high-frequency generator which is turned ON or OFF by the surgeon by actuating a switch. When the high frequency is on, the cutting loop very easily and almost without encountering resistance cuts through the body tissue. However, certain drawbacks accompany the easy, nearly effortless cutting with such an electrode. The surgeon is required to concentrate on the surgery and always must know precisely how deeply he may cut. Unplanned motion or faulty estimation of the desired safe depth of cut lead to unwanted injury to the patient.
In the conventional electrode drive design, such a cutting electrode, when in the rest position, is inside the tubular shaft of the resectoscope. It may be advanced from the distal shaft end to the front where it can be moved to-and-fro. With the high-frequency power turned ON, cutting can be accomplished by moving the electrode with its cutting loop forward and back. In the immediate vicinity of the resectoscope shaft, the possible cutting depth is inherently limited by how the shaft rests. However, the more the loop moves away from the shaft, the deeper the possible cut, and the greater the risk of cutting excessively deeply. Moreover, there is danger of cutting too much forward, i.e., in the direction away from the shaft.